The present invention relates to a novel structure for resiliently biasing the conductive shoe of a trolley or like vehicle into gliding contact with a current conducting rail assembly in order to provide operating power to the trolley.
Trolleys running on a pair of tracks usually receive power from an electrically charged, conducting rail extending parallel thereto. Furthermore, trolleys usually include some type of conductive shoe assembly which is biased into gliding contact with the conducting rail. A problem arises when the distance between the trolley and the conducting rail varies, which may result during movement or abrupt stop and start motions of the trolley. To ensure that the shoe remains in contact with the conducting rail as the distance changes therebetween, prior art devices have employed an independent spring assembly to bias the shoe into gliding contact with the rail.
For example, a known assembly uses a rhomboid linkage system between the trolley and the shoe, with two parallel rods being attached to the shoe by means of swivel joints. A separate spring stretched between the shoe and the trolley extends diagonally across the parallel rods, with the spring functioning to bias a shoe skid into contact with the conducting rail. This assembly has proven less than adequate for several reasons. The relatively large number of separate joints required for the assembly makes it difficult to properly guide the shoe along the conducting rail during movement of the trolley. The excessive number of parts, including the separate spring, are relatively complicated to assemble and costly to manufacture. Finally, the electrical insulation required between the skid and the trolley is especially costly because all of the insulation must be arranged within the conductive shoe. This also acts to increase the overall weight of the shoe causing possible inadvertent separation from the conducting rail.
As will be discussed in detail hereafter, applicant's new and useful device solves the problems confronting the prior art, by providing an inexpensive assembly for resiliently biasing a light-weight conductive shoe into engagement with an electrically charged rail, with the biasing members also providing electrical insulation between the shoe and trolley.